1. Field of the Invention
This invention relates generally to configurations bits and, more specifically, to a circuit wherein unused configuration bits may be powered down to minimize power consumption without having to program the unused configuration bits.
2. Description of the Prior Art
Most processors have one or more peripheral modules. These peripheral modules will generally have a primary configuration bit. The primary configuration bits are used to enable/disable the different peripheral modules. In many cases, the peripheral modules will further have one or more secondary configuration bits. These secondary configuration bits are used to "configure" (i.e., calibrate) the peripheral modules. The secondary configuration bits are used to fine tune elements within the peripheral modules such as resistors, current sources, and other like elements. In many applications, the primary and secondary configuration bits are programmable fuses such as EPROM and EEPROM fuses.
One limitation of configuration bits is that when the configuration bits are unprogrammed, they may draw current. A peripheral module is disabled by programming the corresponding enable/disable configuration bit. When this is done, the corresponding configuration bits that are used to calibrate the peripheral module are no longer necessary. However, if left unprogrammed, the unprogrammed configuration bits will continue to draw current.
Therefore, a need existed to provide a circuit for powering down configuration bits. The circuit would allow any unused configuration bits to be powered down to minimize current consumption when the corresponding peripheral modules are not in use. The circuit would further allow any unused configuration bits to be powered down to minimize current consumption without having to program the unused configuration bits.